Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$127.41	7.625%	$137.125	$137.13	$137.15	$137.10
Purchase #2	$156.95	5.357%	$165.3578	$165.36	$165.35	$165.40
Purchase #3	$97.79	7.446%	$105.0714	$105.07	$105.05	$105.10
Purchase #4	$63.42	9.760%	$69.6098	$69.61	$69.60	$69.60
Purchase #5	$179.99	6.278%	$191.2898	$191.29	$191.30	$191.30
Purchase #6	$186.64	5.205%	$196.3546	$196.35	$196.35	$196.40
Purchase #7	$149.84	9.602%	$164.2276	$164.23	$164.25	$164.20
7 purchase totals =	$962.04		$1,029.0360	$1,029.04	$1,029.05	$1,029.10